Not long ago, the only communication service in a residence was plain old telephone service (POTS). A residence typically had a single telephone connected within the residence via a single piece of twisted pair telephone line to a network interface demarcation (NID) point outside the residence. With such a configuration there were essentially no opportunities for interfering signals and/or incorrect cross connection of telephone lines. As time progressed, more phones were added to residences using a variety of wiring topologies, e.g., star, home run, daisy chain, etc. The combinations present in residences today are nearly endless, and many homeowners are not fully aware of how the telephone wiring in their home is connected. As time further progressed, advanced homeowners began installing and configuring computer networks to allow multiple computers inside their residence to share files, printers, etc. These home networks were typically installed by knowledgeable, advanced users or paid installers, and utilized a set of wiring parallel to the telephone wiring so that the chances of improper cross connection with existing telephone lines remained minimal.
In recent years, there has been a proliferation of interconnected devices and communication networks within residences—many installed by homeowners with minimal knowledge of the workings of such devices and the communications networks and protocols they utilize. Many homeowners now have access to the public Internet via full-time dedicated broadband connections. For example, FIG. 1 shows a prior art in home network (IHN) 100 including a residential gateway (RG) 105 for receiving and transmitting xDSL (“x” variety of Digital Subscriber Line (DSL)) signals carried across a telephone line 110 that simultaneously carries their POTS. The various xDSL standards define a family of broadband communication technologies carried across a standard telephone line between a telephone operator's central office and a residence or business. Some forms of xDSL, e.g., Asymmetric DSL (ADSL), support simultaneous POTS on the same telephone line. To process the xDSL signals, the RG 105 includes an xDSL processor 115 capable of receiving and transmitting xDSL signals from and to an external network 120 over the telephone line 110. The external network 120 provides access to the public Internet via xDSL, and access to the public switched telephone network (PSTN) via POTS or Voice over Internet Protocol (VoIP) carried in Internet protocol (IP) packets over the xDSL connection.
The xDSL processor 115 is typically connected to the telephone line 110 via the inner pair of wires of a first RJ11 connector 125. As illustrated in FIG. 1, the first RJ11 connector (like all RJ11 connectors) supports the connection of two pairs of wires (i.e., two telephone lines)—an inner pair and an outer pair, shown next to each other in the figure. In subsequent figures, if only one pair of wires is connected to an RJ11 connector only half of the corresponding RJ11 symbol is shown, for example a second RJ11 connector 126. The telephone line 110 simultaneously carries POTS and is further connected via additional telephone lines 110a-b to a plurality of telephones 130, 131, 132 using any number of wiring topologies, e.g., star, home-run, daisy chain, etc. To keep transients associated with POTS (e.g., ring voltages, ring trip transients, etc.) and xDSL from interfering, the IHN 100 further includes a plurality of in-line filters (ILF) 135, 136, 137. The ILF 135, 136, 137 provide a low-pass filter (LPF) response between the telephone lines 110a-b and the telephones 130, 131, 132 to keep POTS transients from causing interference with higher frequency xDSL signals, and vice versa. The xDSL processor 115 typically includes a high-pass filter (not shown) to further limit interference between POTS transients and xDSL signals. Example implementations of the xDSL processor 115 and the ILF 135, 136, 137 are well known to persons of ordinary skill in the art and, in the interest of brevity, will not be discussed further.
The RG 105 includes a router/switch/bridge 140 to connect user data transported using IP packets by the xDSL signals with a VoIP processor 145 or an Ethernet transceiver 150. The VoIP processor 145 is capable of communicating voice band data (VBD) signals with a second plurality of telephones 133,134 via an additional telephone line 111. The VoIP processor 145 comprises an analog terminal adapter (ATA) and a pulse coded modulation (PCM) coder-decoder (codec). The ATA transforms digital VBD samples received in IP packets from the external network 120 into PCM encoded digital samples. The PCM encoded samples are converted to analog signals by the PCM codec. Likewise, the PCM codec converts analog signals into PCM encoded digital samples, and the ATA transforms the digital samples into IP packets for transport across the telephone line using xDSL signals to the external network 120. The analog signals to and from the PCM codec are connected to a subscriber line interface circuit (SLIC) 147. The SLIC 147 implements, among other things, a 4-wire to 2-wire hybrid function between the two analog signals (transmit and receive) associated with the PCM codec (i.e., a 4-wire signal) and a 2-wire signal (bi-directional) required for the telephone line 111. The SLIC 147 is connected to the second telephone line 111 via either the inner or outer pair of the second RJ11 connector 126. Alternatively, the SLIC 147 may be connected to the outer pair of the RJ11 connector 125. To provide battery feed voltage and to allow the VoIP processor 145 to ring one or more of the telephones 133,134, the RG 105 includes a battery/ring generator 155. The battery/ring generator 155 supplies a −48 volts (V) direct current (DC) battery feed voltage for use by the telephones 133,134 and also supplies alternating current (AC) ring voltages that may be superimposed on top of the battery feed voltage to ring the telephones 133,134.
The Ethernet transceiver 150 is capable of communicating Ethernet signals (e.g., IEEE 802.3, IEEE 802.3u, IEEE 802.3z, IEEE 802.3ae, etc.) with one or more computers 160 via a computer cable 112 (e.g., unshielded twisted pair (UTP) Category 5 (Cat5) cabling). The Ethernet transceiver 150 is connected to the computer cable 112 via an RJ45 connector 127. The example IHN 100 further includes another telephone line 113 providing POTS to a third plurality of telephones 165,166.
Example implementations of the router/switch/bridge 140, the VoIP processor 145 (including ATA and PCM codec), the SLIC 147, the Ethernet transceiver 150, the computer line 112, the battery/ring generator 155, and the computer 160 are well known to persons of ordinary skill in the art and, thus, will not be discussed further.
FIG. 2 shows the example IHN 100 of FIG. 1 in which the user has incorrectly or inadvertently connected the telephone line 111 to the telephone line 110a via a telephone line 214. The telephone line 214 creates a condition in which both the RG 105 and the external network 120 (i.e., the PSTN 120) are providing battery feed voltage to the telephone lines 110, 110a-b, 111, 214. Depending upon relative polarities of batteries of the RG 105 and the PSTN 120, the telephone lines 110, 110a-b, 111, 214 may experience a net battery feed voltage of −96V or 0V. The former represents a dangerous condition due to excess voltage present on the telephone lines 110, 110a-b, 111, 214. The latter represents a condition in which no battery feed voltage is present and, thus, one or more of the telephones 130-134 may not operate correctly. The incorrect/inadvertent connection 214 may further create interference between a sealing current provided by the PSTN 120 and the battery feed voltage provided by the RG 105.
FIG. 3 shows the example IHN 100 of FIG. 1 further supporting Home PhoneLine Networking Alliance (HomePNA) communications within the IHN 100. HomePNA is a high-speed, reliable local area network (LAN) technology that uses the existing telephone wires in a residence, and allows several computers to share a single Internet connection. To support HomePNA communications, the RG 105 further includes a HomePNA processor 305 to communicate HomePNA signals with, for example, a computer 310 and a HomePNA enabled phone 315. The HomePNA signals are carried across a telephone line 320, that the HomePNA processor 305 is connected to via either an inner or an outer pair of wires of an RJ11 connector 322. Example implementations of the HomePNA processor 305 are well known to persons of ordinary skill in the art, and will not be discussed further.
In the example of FIG. 3, the telephone line 320 is connected to the telephone line 110a via a telephone line 325. The telephone line 325 may have been connected purposefully by a user so that HomePNA devices attached to the telephone line 110a-b can communicate with the HomePNA processor 305, or so that ordinary telephones attached to the telephone line 320 can communicate with the PSTN 120. The connection 325 may also have been made unintentionally by the user. However, because HomePNA signals and VDSL signals may spectrally overlap (depending upon the version of the HomePNA standard being implemented by the HomePNA processor 305), the connection 325 may cause HomePNA signals to interfere with any VDSL signals present on the first telephone line 110. Such interference may cause one or both of the xDSL processor 115 or the HomePNA processor 305 to be unable to communicate properly with attached devices.
FIG. 4 shows an example prior art IHN 400 including a residential gateway (RG) 402 for receiving and transmitting signals carried across a cable 410 from an external network (not shown). To communicate with the external network, the RG 105 includes a transceiver 405 to transmit and receive signals received over the cable 410 (e.g., coaxial cable or UTP Cat5 cable). The signals may be Ethernet signals (e.g., IEEE 802.3, IEEE 802.3u, IEEE 802.3z, IEEE 802.3ae, etc.), xDSL signals over coaxial cable, or multimedia over cable association (MOCA) signals. In the example of FIG. 4, because there are no xDSL signals present on the telephone line 110, there is no need for in line filters, and there is no potential interference between HomePNA signals and VDSL signals. Example implementations of the transceiver 405 for Ethernet, xDSL over coaxial cable, and/or MOCA are well known to persons of ordinary skill in the art, and, thus, will not be discussed further.
FIG. 5 shows a table illustrating the combinations of signals in the example in home networks of FIGS. 1-4 may cause interference when the signals are on the same wire/cable/telephone line. Each entry in the table contains a value of NA, OK, or BAD. An entry of NA (i.e., not applicable) is used if there is no possibility of interference because the two signals are carried on two types of wire/cable/telephone line that can not be physically connected to each other (using the standard and appropriate connectors designed for each wire/cable/telephone line). For example, WAN Ethernet is carried over UTP Cat5 cable with an RJ45 connector and xDSL over coaxial cable is carried over coaxial cable with an F-connector. In FIG. 5, an entry of NA is also used when the two signals types could not possibly be present at the same time, for example, a residence would not simultaneously be subscribing to ADSL and VDSL service over the same telephone line. An entry of OK is used if the signals are carried over the same type of wire/cable/telephone line, but the two signals would not interfere (e.g., they do not spectrally overlap), for example, ADSL uses frequencies above 35 kiloHertz (kHz) and POTS uses frequencies below 4 kHz, and, therefore, these two signals can coexist on the same telephone line without fear of interference. Finally, an entry of BAD in FIG. 5 indicates signals that would interfere. For example, VDSL uses frequencies between 100 kHz and 12 MegaHertz (MHz) and HomePNA version 2 uses frequencies between 4 MHz and 10 MHz. A new HomePNA standard (i.e., version 3) was developed with spectral masks to limit interference between VDSL and HomePNA version 3 signals.
As will be readily appreciated by those having ordinary skill in the art, it is desirable to provide as much functionality as possible while minimizing or eliminating the possibility of interference.